test: add unit tests for editor utilities

[poaspergillus]

Fixes #1298

Summary

• Add unit tests for the exported editor utilities
• Cover all four editor templates and their required fields
• Verify template insertion for supported IDs and no-op behavior for invalid IDs
• Cover typical, midnight, and noon time formatting cases

Validation

• Focused Vitest: 12/12 tests passed
• TypeScript: passed
• Prettier: passed
• ESLint: passed with no errors
• git diff --check: passed

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